1. Field of the Invention
The present invention relates to a track calculation method, and more particularly, to a track calculation method for fixing track jumps of optical discs of different capacities.
2. Description of the Prior Art
Popular optical discs have different capacities so that the optical discs may be classified into normal optical discs and compression optical discs. A compression optical disc is an optical disc storing data in a compressed manner. For example, a track density of a conventional optical disc is raised for raising a capacity of the conventional optical disc so that said conventional optical disc is fabricated as a compression optical disc. A primary characteristic of a compression disc lies in the fact that a track pitch of the compression optical disc is shorter than a track pitch of a conventional optical disc. Moreover, a length of the track pitch of the compression optical disc may be varied corresponding to different compression techniques.
Take video optical discs as examples. Since a conventional optical disc driver is designed for accessing a normal video optical disc, which stores data in an un-compressed manner, and since properties of a compression video optical disc, such as a number of tracks or a length of track pitch, are far from those of a normal video optical disc, when the conventional optical disc driver tries to access a compression optical disc and performs track jumps for accessing arbitrary video sectors on the compression optical disc, a large number of calculation errors result. Therefore, as a result, more track jumps are required, and more time is consumed on seeks between tracks. In other words, a distance on the compression video optical disc between a current location of a pickup unit of the conventional optical disc driver and a designated location of a user is getting broader as well after a track jump is performed. For a user who gets used to the track jump function of the conventional optical disc driver for browsing videos of arbitrary times on a same compression video optical disc, time-consuming or frequent track jumps may bring inconveniences to the user. Besides, properties, which include a capacity, a track pitch, a number of tracks, are varied corresponding to different compression optical discs. Therefore, when a conventional optical disc driver performs track jumps on the different compression optical discs, the frequency and the duration of track jumps are harder to be predicted.